SURFACE ELECTRON MOTION NEAR MONATOMIC STEPS - 2-PHOTON PHOTOEMISSION-STUDIES ON STEPPED CU(111)

The electronic structure of three surface or near-surface states on st epped Cu(775) has been investigated using angle-resolved, resonant, tw o-photon photoemission. Since the electron wave function in each of th ese electronic states has a different average distance from the crysta l plane, the measurement allowed the step potential at each distance t o be sampled. The energy dispersion of the n=1 image-potential state w as found to be oriented by the (111) terrace and the n=2 state was ori ented by the (775) surface plane. The band structure of the embedded s p-like surface state (n=0) was determined by the projection of the bul k band gap onto Cu(775).